4 THE NOSE AND PARANASAL SINUSES

plexus, but some veins join the superior ophthalmic vein in the orbit, while
others enter the anterior facial vein. Lymphatic vessels from the anterior part
of the cavity join cutaneous lymphatics to the submandibular glands, and so
to the sugenpj^deejp cervical glands. Posteriorly the lymphatic drainage is to
the mejSal J.e^_cerv|caf glands.

Tfie nasal mucous membrane consists of a layer of fairly dense connective
tissue containing large blood vessels and some unstriped muscle fibres. There

Fig. 3. Lateral wall of left nasal cavity, showing the conchae or turbinate bodies, the meatuses and
spheno-ethmoidal recess. 1, Right sphenoidal sinus; 2, Sphenoidal ostium; 3, Left sphenoidal sinus; 4,
Superior meatus; 5, Inferior meatus; 6, Inferior concha; 7, Accessory ostium of maxillary sinus; 8*
Middle concha; 9, Superior concha; 10, Frontal sinus; 11, Ostium of posterior ethmoidal cells; 12,
Spheno-ethmoidal recess.

is erectile tissue comprising irregular thin-walled blood spaces in the anterior
and posterior ends of the inferior concha. A layer of elastic tissue fibres is
present beneath the basement membrane, and this layer allows the mucosa to
return to normal size when the vascular engorgement of the erectile tissue has
worn off. The surface epithelium is columnar ciliated lying upon several
layers of cuboidal cells resting upon the basement membrane. There are many
mucous glands beneath the basement membrane, their ducts penetrating the
membrane to open on the surface.

There are two nerve supplies to the nasal cavity, sensory and secretory.
The main sensory nerve supply is derived from the maxillary division of the
trigeminal nerve through branches arising in the pterygopalatine ganglion
(fig. 8). The lateral and medial internal nasal branches of the ophthalmic
nerve supply the anterior part of the nasal cavity, while the floor and anterior